when I use Ccleaner, it erease even the Oulook files indexing.
Since I've more then 50.000 emails stored in it, every time I have to wait something like 4 or 5 hours to get a new files index (for search fast the emails in all the folders).
Windows Event Logs, Old Prefetch data, Menu Order Cache, Tray Notifications Cache, Windows Size/Location Cache, Environment Path, User Assist History, Custom Files and Folders, and Wipe Free Space.
I don't see anything that looks like it would effect Outlook indexes (but I'm happy to be wrong).